We converted officewiki talk pages to Flow, moving/archiving the existing wikitext and putting a "Previous discussion was archived at ..." link to it in the Flow board header.
However, links to these discussion pages appeared as redlinks, falsely indicating the page doesn't exist. Here are two examples, however once you follow the redlink, you see the Flow board's content and the wiki no longer displays the redlink.
- on a #REDIRECT page, the link to the proper Flow board is red.
- on a user page, the [Discussion] tab link to the User_talk page is red.
Note that when you follow these links, Flow creates a page revision (ensureFlowRevision) and so the link to the Flow board is no longer red. Heisenbug.